Malic acid

Malic acid, also known as 2-hydroxysuccinic acid, has two stereoisomers because of an asymmetric carbon atom in the molecule.

In nature, it occurs in three forms, D-malic acid, L-malic acid, and its mixture, DL-malic acid.White crystal or crystalline powder, with strong hygroscopicity, easy to dissolve in water and ethanol.It has a particularly pleasant sour taste.Malic acid is used mainly in the food and pharmaceutical industries.

SECURITY:

Malic acid is a component of apples. The daily intake of malic acid from vegetables and fruits is about 1.5 ~ 3.0g, and no adverse reactions have been found, with extremely low toxicity.

QUALITY INDICATORS:

According to The Japanese food additive standard, malic acid should meet the following quality indexes: content ≥ 99.0% (quality), dissolved, aqueous solution clarified, melting point 127 ~ 130℃, heavy metal ≤ 0.002% (quality), chloride ≤ 0.0035% (quality), iron ≤ 0.004% (quality), and burning residue ≤ 0.05% (quality).[1]

According to the U.S. Food Chemicals Code (1983), malic acid shall meet the following quality indicators: content ≥ 99.5% (quality).Melting point 130 ~ 132℃, ash ≤ 0.1% (mass), heavy metal (in Pb)≤ 0.002% (mass), arsenic (in As)≤ 0.0003% (mass), lead ≤ 0.001% (mass), Fumaric acid ≤ 0.5% (mass), maleic acid ≤ 0.05% (mass), water insoluble ≤ 0.1 ‰(mass)

PRODUCTION METHODS:

At present, the production methods of L-malic acid have been developed from the early single extraction method to the following methods: extraction method, chemical synthesis method, one-step fermentation method, two-step fermentation method, immobilized enzyme or cell transformation method [2].At present, the existing problem is still the lack of excellent production strains, in the study of breeding excellent strains at the same time, pay attention to strengthen the extraction process and other related technology research, do well the research and development of upstream and downstream engineering supporting technology is very necessary.